Has the time come for age-adapted glomerular filtration rate criteria to define chronic kidney disease: how soon is now?

PURPOSE OF REVIEW: The conventional definition of chronic kidney disease (CKD) primarily relies on the identification of albuminuria or a decline in estimated glomerular filtration rate (eGFR). For many years, a straightforward eGFR threshold of <60 ml/min/1.73 m 2 has been widely adopted as the standard for defining CKD. Nonetheless, this criterion fails to consider the natural aging process of the kidney, and this oversight may affect the accurate diagnosis of kidney disease particularly at the extremes of age. RECENT FINDINGS: The fixed eGFR threshold of <60 ml/min/1.73 m 2 for defining CKD misses crucial opportunities for risk prevention. Studies have revealed that the eGFR threshold at which the risks for adverse long-term health outcomes such as mortality, cardiovascular events, and kidney failure begin to rise varies substantially by age. Specifically, this threshold is lower for the elderly and higher for young adults. Consequently, this results in the over-diagnosis of kidney disease in the elderly and the under-diagnosis of kidney disease in young adults. SUMMARY: To address these limitations of the current CKD definition, we discuss a number of proposed age-adapted eGFR criteria and weigh their pros and cons against the current, simple, and universally accepted approach.

Pre-Pregnancy eGFR and the Risk of Adverse Maternal and Fetal Outcomes: A Population-Based Study.

SIGNIFICANCE STATEMENT: Pregnancies in women with CKD carry greater risk than pregnancies in the general population. The small number of women in prior studies has limited estimates of this risk, especially among those with advanced CKD. We report the results of a population-based cohort study in Ontario, Canada, that assessed more than 500,000 pregnancies, including 600 with a baseline eGFR < 60 ml/min per 1.73 m 2 . The investigation demonstrates increases in risk of different adverse maternal and fetal outcomes with lower eGFR and further risk elevation with baseline proteinuria. BACKGROUND: CKD is a risk factor for pregnancy complications, but estimates for adverse outcomes come largely from single-center studies with few women with moderate or advanced stage CKD. METHODS: To investigate the association between maternal baseline eGFR and risk of adverse pregnancy outcomes, we conducted a retrospective, population-based cohort study of women (not on dialysis or having had a kidney transplant) in Ontario, Canada, who delivered between 2007 and 2019. The study included 565,907 pregnancies among 462,053 women. Administrative health databases captured hospital births, outpatient laboratory testing, and pregnancy complications. We analyzed pregnancies with serum creatinine measured within 2 years of conception up to 30 days after conception and assessed the impact of urine protein where available. RESULTS: The risk of major maternal morbidity, preterm delivery, and low birthweight increased monotonically across declining eGFR categories, with risk increase most notable as eGFR dropped below 60 ml/min per 1.73 m 2 . A total of 56 (40%) of the 133 pregnancies with an eGFR <45 ml/min per 1.73 m 2 resulted in delivery under 37 weeks, compared with 10% of pregnancies when eGFR exceeded 90 ml/min per 1.73 m 2 . Greater proteinuria significantly increased risk within each eGFR category. Maternal and neonatal deaths were rare regardless of baseline eGFR (<0.3% of all pregnancies). Only 7% of women with an eGFR <45 ml/min per 1.73 m 2 received dialysis during or immediately after pregnancy. CONCLUSIONS: We observed higher rates of adverse pregnancy outcomes in women with low eGFR with concurrent proteinuria. These results can help inform health care policy, preconception counseling, and pregnancy follow-up in women with CKD.

Short Timeframe Prediction of Kidney Failure among Patients with Advanced Chronic Kidney Disease.

BACKGROUND: Development of a short timeframe (6-12 months) kidney failure risk prediction model may serve to improve transitions from advanced chronic kidney disease (CKD) to kidney failure and reduce rates of unplanned dialysis. The optimal model for short timeframe kidney failure risk prediction remains unknown. METHODS: This retrospective study included 1757 consecutive patients with advanced CKD (mean age 66 years, estimated glomerular filtration rate 18 mL/min/1.73 m2). We compared the performance of Cox regression models using (a) baseline variables alone, (b) time-varying variables and machine learning models, (c) random survival forest, (d) random forest classifier in the prediction of kidney failure over 6/12/24 months. Performance metrics included area under the receiver operating characteristic curve (AUC-ROC) and maximum precision at 70% recall (PrRe70). Top-performing models were applied to 2 independent external cohorts. RESULTS: Compared to the baseline Cox model, the machine learning and time-varying Cox models demonstrated higher 6-month performance [Cox baseline: AUC-ROC 0.85 (95% CI 0.84-0.86), PrRe70 0.53 (95% CI 0.51-0.55); Cox time-varying: AUC-ROC 0.88 (95% CI 0.87-0.89), PrRe70 0.62 (95% CI 0.60-0.64); random survival forest: AUC-ROC 0.87 (95% CI 0.86-0.88), PrRe70 0.61 (95% CI 0.57-0.64); random forest classifier AUC-ROC 0.88 (95% CI 0.87-0.89), PrRe70 0.62 (95% CI 0.59-0.65)]. These trends persisted, but were less pronounced, at 12 months. The random forest classifier was the highest performing model at 6 and 12 months. At 24 months, all models performed similarly. Model performance did not significantly degrade upon external validation. CONCLUSIONS: When predicting kidney failure over short timeframes among patients with advanced CKD, machine learning incorporating time-updated data provides enhanced performance compared with traditional Cox models.

Social determinants of health and the transition from advanced chronic kidney disease to kidney failure.

BACKGROUND: The transition from chronic kidney disease (CKD) to kidney failure is a vulnerable time for patients, with suboptimal transitions associated with increased morbidity and mortality. Whether social determinants of health are associated with suboptimal transitions is not well understood. METHODS: This retrospective cohort study included 1070 patients with advanced CKD who were referred to the Ottawa Hospital Multi-Care Kidney Clinic and developed kidney failure (dialysis or kidney transplantation) between 2010 and 2021. Social determinant information, including education level, employment status and marital status, was collected under routine clinic protocol. Outcomes surrounding suboptimal transition included inpatient (versus outpatient) dialysis starts, pre-emptive (versus delayed) access creation and pre-emptive kidney transplantation. We examined the association between social determinants of health and suboptimal transition outcomes using multivariable logistic regression. RESULTS: The mean age and estimated glomerular filtration rate were 63 years and 18 ml/min/1.73 m2, respectively. Not having a high school degree was associated with higher odds for an inpatient dialysis start compared with having a college degree {odds ratio [OR] 1.71 [95% confidence interval (CI) 1.09-2.69]}. Unemployment was associated with higher odds for an inpatient dialysis start [OR 1.85 (95% CI 1.18-2.92)], lower odds for pre-emptive access creation [OR 0.53 (95% CI 0.34-0.82)] and lower odds for pre-emptive kidney transplantation [OR 0.48 (95% CI 0.24-0.96)] compared with active employment. Being single was associated with higher odds for an inpatient dialysis start [OR 1.44 (95% CI 1.07-1.93)] and lower odds for pre-emptive access creation [OR 0.67 (95% CI 0.50-0.89)] compared with being married. CONCLUSIONS: Social determinants of health, including education, employment and marital status, are associated with suboptimal transitions from CKD to kidney failure.

Performance of the 2021 Race-Free CKD-EPI Creatinine- and Cystatin C-Based Estimated GFR Equations Among Kidney Transplant Recipients.

RATIONALE & OBJECTIVE: Race-free estimated glomerular filtration rate (eGFR) equations incorporating creatinine with and without cystatin C were recently developed and recommended for routine use. However, the performance of these equations among kidney transplant recipients (KTRs) remains unknown. STUDY DESIGN: Cross-sectional study to validate the 2021 race-free Chronic Kidney Disease (CKD) Epidemiology Collaboration (CKD-EPI) eGFR equation based on creatinine alone (eGFRcr) or based on creatinine and cystatin C (eGFRcr-cys) among KTRs. SETTING & PARTICIPANTS: KTRs in stable condition (N = 415) from Canada and New Zealand with same-day measurements of creatinine, cystatin C, and glomerular filtration rate (GFR) using radiolabeled diethylenetriaminepentaacetic acid. TESTS COMPARED: The 2009 CKD-EPI eGFRcr, 2021 CKD-EPI eGFRcr, 2012 CKD-EPI eGFRcr-cys, 2021 CKD-EPI eGFRcr-cys, 2012 CKD-EPI eGFRcys, and Modification of Diet in Renal Disease (MDRD) Study eGFR equations were compared with measured GFR. OUTCOMES: Bias, precision, accuracy, and correct classification by CKD stage. Bias was defined as the difference between estimated and measured GFR. Precision was represented by the interquartile range. Accuracy was defined as the percentages of participants with eGFRs within 10%/20%/30% (P10/P20/P30) of measured GFR, root mean square error, and mean absolute error. RESULTS: 87% of patients studied were White, 3% Black, and 10% other races. Mean measured GFR was 53 ± 19 (SD) mL/min/1.73 m2. The 2009 and 2021 CKD-EPI eGFRcr equations demonstrated similar median bias (-2.3 vs -0.2 mL/min/1.73 m2, respectively), precision (14.5 vs 14.9 mL/min/1.73 m2), and accuracy (P10/P20/P30, 32%/65%/84% vs 33%/63%/84%). The 2012 and 2021 CKD-EPI eGFRcr-cys equations also demonstrated similar median bias (-3.6 vs 0.3 mL/min/1.73 m2, respectively), precision (13.3 vs 14.3 mL/min/1.73 m2), and accuracy (P10/P20/P30, 32%/63%/80% vs 32%/67%/83%). No clear difference in performance was detected between the 2021 CKD-EPI eGFRcr and eGFRcr-cys equations among KTRs. The proportion of correct classification by CKD stage was similar across all eGFR equations. LIMITATIONS: Moderate sample size, few patients had a GFR <30 mL/min/1.73 m2, and the large majority of patients were White. CONCLUSIONS: Among KTRs, the 2021 race-free CKD-EPI eGFR equations perform similarly to the previous CKD-EPI equations that included race correction terms. No significant difference in performance was observed between the 2021 CKD-EPI eGFRcr and eGFRcr-cys equations in the kidney transplant population.

Simultaneous glomerular filtration rate determination using inulin, iohexol, and 99mTc-DTPA demonstrates the need for customized measurement protocols.

Urinary inulin clearance is considered the gold standard of glomerular filtration rate (GFR) measurement but plasma clearance of less expensive and more accessible tracers is more commonly performed. Many plasma sampling protocols exist but little is known about their accuracy. Here, the study objectives were to compare plasma iohexol and 99mTc-DTPA GFR with varying sampling strategies to the GFR measured by urinary inulin and to identify protocols with the greatest accuracy according to clinical characteristics. GFR was measured simultaneously using urinary inulin, plasma iohexol, and plasma 99mTc DTPA clearance. Blood was sampled from 2 to 10 hours after injection. For each method, bias, precision, and accuracy (P30 and mean absolute error) were calculated for the entire cohort and for eGFR-EPI creatinine subgroups (<30, 30-59, and ≥60 ml/min/1.73m2) and the edema stage using urinary inulin clearance as the gold standard. The mean inulin GFR of the 77 participants was 33 ml/min/1.73m2. Delay of both the initial and the final samples in plasma iohexol protocols yielded the highest accuracy in the setting of low GFR (<30 ml/min/1.73m2). Early initial and final samples yielded the highest accuracy in the setting of high GFRs (≥60 ml/min/1.73m2). No sampling strategy was accurate in edematous patients. Thus, our study demonstrates that customization of GFR protocols according to the anticipated level of GFR are required to optimize protocol accuracy.

A living donor kidney transplant recipient with mycobacterium senegalense bacteremia: A case report.

Mycobacterium senegalense is primarily known in sub-Saharan Africa to cause bovine farcy, a chronic granulomatous inflammation of the skin and lymphatics in cows. Reports of M. senegalense are rare among humans. We report a unique case of M. senegalense bloodstream infection in a living donor kidney transplant recipient with multiple possible sources of infection.

Accurate determination of glomerular filtration rate in adults for carboplatin dosing: Moving beyond Cockcroft and Gault.

OBJECTIVE: Carboplatin is a cytotoxic chemotherapy drug developed in the 1980s which is still widely used today across various tumour types. Despite its common application, there remains a significant controversy and practice variation on its unique method of dosing by area under the curve (AUC). One potential reason for this variability stems from the reliance of using an estimated glomerular filtration rate (eGFR) as an extrapolation of the measured GFR (mGFR) which the commonly used Calvert equation was originally validated for. This review takes a novel and collaborative nephro-oncology approach to highlight the historical evolution of carboplatin dosing, methods for estimating GFR and its relative performance in the application of carboplatin dosing for adult patients. DATA SOURCES: We reviewed all pertinent publications comparing carboplatin AUC-based dosing in adult patients based on the various methods of GFR measurements or estimations in order to provide a comprehensive description of each method's advantages and risks. DATA SUMMARY AND CONCLUSIONS: The Cockcroft-Gault equation has been widely studied but newer eGFR equations, such as the CKD-Epidemiology Collaboration (CKD-EPI) or Janowitz-Williams equation have outperformed the Cockcroft-Gault in recent studies.

Safety and Efficacy of Tinzaparin Anticoagulation during Nocturnal Hemodialysis.

BACKGROUND: The safety and efficacy of low-molecular-weight heparin in the prevention of extracorporeal dialysis circuit clotting among in-center extended duration nocturnal hemodialysis (INHD) patients are unknown. The aim of this study was to determine the safety and efficacy of 2 doses of tinzaparin, among INHD patients receiving 6-8 h hemodialysis, 3 times per week. METHODS: We conducted a retrospective cohort study to examine antifactor Xa levels at time 0, 2 h, 4 h mid-hemodialysis (mid-HD), 6 h, and at end of each INHD session for 4 weeks and to determine extracorporeal dialysis circuit clotting and bleeding events after switching from unfractionated heparin to tinzaparin, using a standard protocol of tinzaparin delivery at the initiation and midpoint of HD. RESULTS: All 16 patients in The Ottawa Hospital INHD program were converted to tinzaparin and followed for 177 INHD sessions. Mean antifactor Xa level at 2 h of HD was 0.41 ± 0.21 (SD) IU/mL, at 4 h (mid-HD) 0.19 ± 0.17 IU/mL, at 6 h 0.44 ± 0.21 IU/mL, and at dialysis end 0.26 ± 0.14 IU/mL. Antifactor Xa levels were undetectable at the start of INHD, suggesting no tinzaparin accumulation. Five patients required an increase in tinzaparin due to extracorporeal dialysis circuit clotting. There were no bleeding events. One patient required a switch to fondaparinux due to an adverse reaction. CONCLUSION: Tinzaparin was safe and efficacious for most INHD patients without accumulation or bleeding. The conversion from unfractionated heparin to tinzaparin required an increased tinzaparin dose for 31% of INHD patients.

Serum BTP concentrations are not affected by hepatic dysfunction.

BACKGROUND: Beta Trace Protein (BTP) is a promising marker of glomerular filtration rate (GFR). Equations to estimate GFR using BTP have been proposed. Very little is known about BTP's production and metabolism. It has been hypothesized that the liver metabolizes certain BTP isoforms. As such, hepatic dysfunction may influence serum levels independently of GFR. This would impact on the accuracy and precision of GFR estimates using BTP. The purpose of this study was to assess the impact of cirrhosis on serum BTP concentrations. METHODS: BTP, cystatin C (cysC) and creatinine (Cr) were measured in 99 cirrhotic subjects and in matched controls. BTP/cysC and Cr/cysC ratios were compared between cases and controls. This was repeated after stratification by Child Pugh category. Comparisons of ratios between Child Pugh category A and combined B and C case subjects were also performed. RESULTS: There were no differences in BTP/cysC ratios between cases and controls for the entire cohort (0.80 vs 0.79) or for any of the Child Pugh categories (p > 0.10). There were significant differences between cases (1.09) and controls (0.73) for the BTP/Cr ratios (p < 0.001). The BTP/Cr ratio was higher in those with more advanced cirrhosis as compared to those with less severe cirrhosis (1.20 vs 1.03, p < 0.01). There were no differences in BTP/cysC ratios between those with less severe and more advanced cirrhosis (p = 0.25). CONCLUSIONS: This study suggests that hepatic dysfunction does not influence serum BTP levels and argues against a significant role for the liver in BTP metabolism. Confirmation in a larger group of patients with advanced cirrhosis is required.

Geographic and facility variation in initial use of non-tunneled catheters for incident maintenance hemodialysis patients.

BACKGROUND: Non-tunneled (temporary) hemodialysis catheters (NTHCs) are the least-optimal initial vascular access for incident maintenance hemodialysis patients yet little is known about factors associated with NTHC use in this context. We sought to determine factors associated with NTHC use and examine regional and facility-level variation in NTHC use for incident maintenance hemodialysis patients. METHODS: We analyzed registry data collected between January 2001 and December 2010 from 61 dialysis facilities within 12 geographic regions in Canada. Multi-level models and intra-class correlation coefficients were used to evaluate variation in NTHC use as initial hemodialysis access across facilities and geographic regions. Facility and patient characteristics associated with the lowest and highest quartiles of NTHC use were compared. RESULTS: During the study period, 21,052 patients initiated maintenance hemodialysis using a central venous catheter (CVC). This included 10,183 patients (48.3 %) in whom the initial CVC was a NTHC, as opposed to a tunneled CVC. Crude variation in NTHC use across facilities ranged from 3.7 to 99.4 % and across geographic regions from 32.4 to 85.1 %. In an adjusted multi-level logistic regression model, the proportion of total variation in NTHC use explained by facility-level and regional variation was 40.0 % and 34.1 %, respectively. Similar results were observed for the subgroup of patients who received greater than 12 months of pre-dialysis nephrology care. Patient-level factors associated with increased NTHC use were male gender, history of angina, pulmonary edema, COPD, hypertension, increasing distance from dialysis facility, higher serum phosphate, lower serum albumin and later calendar year. CONCLUSIONS: There is wide variation in NTHC use as initial vascular access for incident maintenance hemodialysis patients across facilities and geographic regions in Canada. Identifying modifiable factors that explain this variation could facilitate a reduction of NTHC use in favor of more optimal initial vascular access.

The association of urinary sodium excretion and the need for renal replacement therapy in advanced chronic kidney disease: a cohort study.

BACKGROUND: Restriction of dietary sodium is routinely recommended for patients with chronic kidney disease (CKD). Whether or not sodium intake is associated with the progression of CKD and mortality remains controversial. We evaluated the association of urinary sodium excretion (as a surrogate for sodium intake) on the need for renal replacement therapy and mortality in patients with advanced CKD. METHODS: We conducted a retrospective study of patients followed at a CKD clinic of a tertiary care hospital from January 2010 to December 2012. Adult patients with advanced CKD (estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m(2)) were included. Using a time-to-event analysis, we examined the association of urinary sodium excretion as a continuous and also as a categorical variable (categorized as low sodium diet - LSD (<100 mEq/day), medium sodium diet - MSD (100-150 mEq/day), and high sodium diet - HSD (>150 mEq/day) and the outcomes of interest. The primary outcome was defined as composite of progression to end-stage renal disease requiring any type of renal replacement therapy and mortality. The secondary outcome was change in eGFR/year. RESULTS: 341 patients (82 LSD, 116 MSD and 143 HSD) were included in the study (mean follow up of 1.5 years) with a mean eGFR decline of 2.7 ml/min/1.73 m(2)/year. 105 patients (31 %) required renal replacement therapy and 10 (3 %) died. There was no association between urinary sodium excretion and change in the eGFR or need for renal replacement therapy and mortality in crude or adjusted models (unadjusted HR 1.002; 95%CI 1.000-1.004, adjusted HR 1.001; 95%CI 0.998-1.004). CONCLUSION: In patients with advanced CKD (eGFR < 30 ml/min/1.73 m(2)), sodium intake does not appear to impact the progression of CKD to end-stage renal disease; however, more definitive studies are needed.

Canadian Society of Nephrology commentary on the KDIGO clinical practice guideline for CKD evaluation and management.

We congratulate the KDIGO (Kidney Disease: Improving Global Outcomes) work group on their comprehensive work in a broad subject area and agreed with many of the recommendations in their clinical practice guideline on the evaluation and management of chronic kidney disease. We concur with the KDIGO definitions and classification of kidney disease and welcome the addition of albuminuria categories at all levels of glomerular filtration rate (GFR), the terminology of G categories rather than stages to describe level of GFR, the division of former stage 3 into new G categories 3a and 3b, and the addition of the underlying diagnosis. We agree with the use of the heat map to illustrate the relative contributions of low GFR and albuminuria to cardiovascular and renal risk, though we thought that the highest risk category was too broad, including as it does people at disparate levels of risk. We add an albuminuria category A4 for nephrotic-range proteinuria and D and T categories for patients on dialysis or with a functioning renal transplant. We recommend target blood pressure of 140/90mm Hg regardless of diabetes or proteinuria, and against the combination of angiotensin receptor blockers with angiotensin-converting enzyme inhibitors. We recommend against routine protein restriction. We concur on individualization of hemoglobin A1c targets. We do not agree with routine restriction of sodium intake to <2g/d, instead suggesting reduction of sodium intake in those with high intake (>3.3g/d). We suggest screening for anemia only when GFR is <30mL/min/1.73m(2). We recognize the absence of evidence on appropriate phosphate targets and methods of achieving them and do not agree with suggestions in this area. In drug dosing, we agree with the recommendation of using absolute clearance (ie, milliliters per minute), calculated from the patient's estimated GFR (which is normalized to 1.73m(2)) and the patient's actual anthropomorphic body surface area. We agree with referral to a nephrologist when GFR is <30mL/min/1.73m(2) (and for many other scenarios), but suggest urine albumin-creatinine ratio > 60mg/mmol or proteinuria with protein excretion > 1g/d as the referral threshold for proteinuria.

Trends in Arteriovenous Fistula Use at Dialysis Initiation After Automated eGFR Reporting.

The purpose of this study was to examine trends in the presence of an arteriovenous fistula (AVF) at dialysis initiation before and after eGFR reporting. All incident dialysis patients from four Canadian provinces that implemented province-wide, automated laboratory reporting of eGFR with known vascular access at dialysis initiation were included in the study (N = 25,201) from 2001 to 2010. The primary outcome was the change in proportion of patients with an AVF at dialysis initiation using an interrupted time series and adjusted multilevel logistic regression models. AVF usage at dialysis initiation decreased gradually over the study period from 19.0% to 14.6%. After implementation of automated eGFR reporting, there was attenuation in the decline in AVF usage in models adjusted for case-mix, facility, and the downward trajectory in AVF use over time. The adjusted odds ratio for initiating dialysis with an AVF 1 year post-eGFR reporting compared to pre-eGFR reporting was more pronounced in older patients (age tertile >73; OR: 1.40; 95% CI: 1.04-1.90). Laboratory-based eGFR reporting was associated with a possible attenuation in the decline of AVF at dialysis initiation and this was more pronounced in older patients.

Predicting kidney transplantation outcomes using proteinuria ascertained from spot urine samples versus timed urine collections.

BACKGROUND: Proteinuria has been associated with transplant loss and mortality in kidney transplant recipients. Both spot samples (albumin-creatinine ratio [ACR] and protein-creatinine ratio [PCR]) and 24-hour collections (albumin excretion rate [AER] and protein excretion rate [PER]) have been used to quantify protein excretion, but which measurement is a better predictor of outcomes in kidney transplantation remains uncertain. STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: Tertiary care center, 207 kidney transplant recipients who were enrolled in a prospective study to measure glomerular filtration rate. Consecutive patients who met inclusion criteria were approached. PREDICTORS: ACR and PCR in spot urine samples, AER and PER in 24-hour urine collections. OUTCOMES: Primary outcome included transplant loss, doubling of serum creatinine level, or death. MEASUREMENTS: Urine and serum creatinine were measured using a modified Jaffé reaction that had not been standardized by isotope-dilution mass spectrometry. Urine albumin was measured by immunoturbidimetry. Urine protein was measured by pyrogallol red molybdate complex formation using a timed end point method. RESULTS: Mean follow-up was 6.4 years and 22% developed the primary end point. Multivariable-adjusted areas under the receiver operating characteristic curves were similar for the different protein measurements: ACR (0.85; 95% CI, 0.79-0.89), PCR (0.84; 95% CI, 0.79-0.89), PER (0.86; 95% CI, 0.80-0.90), and AER (0.83; 95% CI, 0.78-0.88). C Index values also were similar for the different proteinuria measurements: 0.87 (95% CI, 0.79-0.95), 0.86 (95% CI, 0.79-0.94), 0.88 (95% CI, 0.82-0.94), and 0.86 (95% CI, 0.77-0.95) for log(ACR), log(PCR), log(PER), and log(AER), respectively. LIMITATIONS: Single-center study. Measurement of proteinuria was at variable times posttransplantation. CONCLUSIONS: Spot and 24-hour measurements of albumin and protein excretion are similar predictors of doubling of serum creatinine level, transplant loss, and death. Thus, spot urine samples are a suitable alternative to 24-hour urine collection for measuring protein excretion in this population.

Spot urine protein measurements in kidney transplantation: a systematic review of diagnostic accuracy.

BACKGROUND: Quantification of proteinuria (albuminuria) in renal transplant recipients is important for diagnostic and prognostic purposes. Recent guidelines have recommended quantification of proteinuria by spot protein-to-creatinine ratio (PCR) or spot albumin-to-creatinine ratio (ACR). Validity of spot measurements remains unclear in renal transplant recipients. METHODS: Systematic review of adult kidney transplant recipients. Studies that reported the diagnostic accuracy of PCR or ACR as compared with 24-h urine protein or albumin excretion in renal transplant recipients were included. RESULTS: The search identified 8 studies involving 1871 renal transplant recipients. The correlation of the PCR to 24-h protein ranged from 0.772 to 0.998 with a median value of 0.92. PCR sensitivity ranged from 63 to 99 (50% of sensitivities were >90%); PCR specificity varied from 73 to 99 (50% of specificities were >90%). Only one study reported the bias; percent bias ranged from 12 to 21% and accuracy (within 30% of 24 h urine protein) ranged from 47 to 56% depending on the degree of proteinuria. For the ACR, percent bias ranged from 9 to 21%, and the accuracy (within 30%) ranged from 38 to 80%. CONCLUSIONS: The data regarding diagnostic accuracy of PCR and ACR is limited. Only one report studied the absolute measures of agreement (bias and accuracy). We recommend verifying PCR and ACR measurements with a 24-h protein before making any major diagnostic (e.g. biopsy) or therapeutic (e.g. change in immunosuppressive agents) decisions in this population.

Social determinants of health and dialysis modality selection in patients with advanced chronic kidney disease: A retrospective cohort study.

BACKGROUND: Social determinants of health are non-medical factors that impact health. For patients with chronic kidney disease (CKD) progressing to kidney failure, the influence of social determinants of health on dialysis modality selection (haemodialysis vs. peritoneal dialysis (PD)) is incompletely understood. METHODS: Retrospective cohort study of 981 consecutive patients with advanced CKD referred to the Ottawa Hospital Multi-Care Kidney Clinic (Canada) who progressed to dialysis from 2010 to 2021. Multivariable logistic regression was used to measure odds ratios (OR) for the associations between social determinants of health (education, employment, marital status and residence) and modality of dialysis initiation. RESULTS: The mean age and estimated glomerular filtration rate were 64 and 18 mL/min/1.73 m2, respectively. Not having a high school degree was associated with lower odds of initiating dialysis via PD compared to having a college degree (29% vs. 48%, OR 0.55 (95% confidence interval (CI) 0.34-0.88)). Unemployment was associated with lower odds of initiating dialysis via PD compared to active employment (38% vs. 62%, OR 0.40 (95% CI 0.27-0.60)). Being single was associated with lower odds of initiating dialysis via PD compared to being married (35% vs. 48%, adjusted OR 0.52 (95% CI 0.39-0.70)). Living alone at home was associated with lower odds of initiating dialysis via PD compared to living at home with family (33% vs. 47%, adjusted OR 0.55 (95% CI 0.39-0.78)). CONCLUSIONS: Social determinants of health including education, employment, marital status and residence are associated with dialysis modality selection. Addressing these 'upstream' social factors may allow for more equitable outcomes during the transition from advanced CKD to kidney failure.